During the advance of computer technology, navigation devices have been widely used for over a decade. The navigation device can, not only determine the driver's current position by utilizing the Global Positioning System (GPS), but also provide different routing information between the vehicle's current position and the destination. In order to perform abovementioned functions, the navigation device is usually equipped with a sophisticated navigation system comprising navigation computer programs and one or more detailed database to store and provide maps, road networks, geographical features, and waypoint or point-of-interest (POI) information.
Recently, connected portable devices (portable navigation devices (PNDs), smartphones, etc.) have become more popular and affordable. Most connected portable devices are equipped with location sensors, such as global positioning system (GPS), cellular or Wi-Fi (Wireless Fidelity) triangulation, that provide turn-by-turn navigation guidance to the user. A common problem with these devices is their rapid consumption of the electrical power stored in the battery when the location sensors are operated, which often results in a disrupted user experience when the devices are off due to insufficient battery power.
Regarding the location accuracy of the abovementioned location sensors, GPS receiver has the highest location accuracy, followed by Wi-Fi and GSM (Global System for Mobile Communication). In terms of power consumption, the same order would be applied to show the power consumption, from the highest to the lowest. As can be seen in FIG. 1 (from Professor Romit Roy Choudhury, Duke University, which is incorporated herein by reference), if the battery life is eight hour when using a GPS receiver, it can be extended to about sixteen hours when using Wi-Fi, and about forty hours when using GSM.
U.S. Pat. No. 7,577,516 to Dobeck et al. discloses a portable data terminal generally comprising a battery, a central controller, a GPS system, and an auxiliary processor. The central controller has a sleep state by which at least some of the functionalities of the central controller are limited to conserve battery power, as shown in FIG. 2. However, Dobeck does not disclose anything related to switching the GPS receiver to other less accurate location sensors such as Wi-Fi or GSM, according to the driver's familiarity of the route or location, or the complexity of the route or location.
Japanese Laid-Open Patent Application No. 2007187620 discloses a method and system to reduce power consumption in a cellular phone with GPS function. More specifically, the GPS will be turned off, and stores a GPS assist signal when arriving at a first reference point. When arriving at a second reference point, the GPS will be again turned on and the stored GPS assist signal will be used for detecting the vehicle's current position. However, like Dobeck, it does not disclose anything related to switching the GPS receiver to other less accurate location sensors such as Wi-Fi or GSM, according to the driver's familiarity of the route or location, or the complexity of the route or location.
Therefore, there remains a need for a new and improved apparatus and method for efficiently using a battery in a mobile phone to provide the highest possible location accuracy to the driver, according to the driver's familiarity of the route or location, or the complexity of the route or location.